JPH10205913A - Magnetic refrigerating machine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the occurrence of partial contact between a cold heat reservoir and a magnetic substance that may occur during the movement of the former so that the effective heat transfer surface area therebetween can be increased and the output of the refrigerating machine, expanded. SOLUTION: A magnetic refrigerating machine is equipped with a magnetic substance 12, superconductive magnet 29 which excites the magnetic substance 12, thermal switch 8 which discharges the heat evolved from the magnetic substance 12 during excitation by the magnet 29, and a cold heat reservoir 13 which by contact with the magnetic substance 12 effects heat exchange. In this instance the magnetic refrigerating machine is one provided with sliding guide members 22a, 22b of low friction coefficient disposed at parts where the magnetic substance 12 has its upper and lower surfaces in contact with the cold heat reservoir 13 and, in addition to the sliding guide members 22a, 22b, with guides 23a, 23b disposed in contact with the upper and lower surfaces of the magnetic substance 12 and designed to suppress its vertical movement.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a magnetic refrigerator using a regenerator.

[0002]

2. Description of the Related Art A conventional Ericsson-type magnetic refrigerator using a magnetic refrigeration cycle including a cold storage process will be described with reference to FIG.

[0003] In FIG. 3, reference numeral 1 denotes an insulated vacuum container for reducing invasion heat, and 2 denotes a flange portion of the insulated vacuum container. Reference numeral 3 denotes a liquid nitrogen tank for shielding radiant heat from a room temperature portion, and reference numeral 4 denotes liquid nitrogen. Reference numeral 5 denotes an auxiliary refrigerator, for example, a GM refrigerator using a Gifford McMahon cycle. Reference numeral 6 denotes a cold head of the auxiliary refrigerator 5, and reference numeral 7 denotes a copper block that thermally connects the movable portion 8 of the exhaust heat switch and the cold head 6.

[0004] The heat removal switch movable section 8 is an electrical insulator for reducing heat generation due to eddy current generated when the magnetic field of the superconducting magnet 29 is changed in a pulsed manner.
Quartz or the like having high thermal conductivity in the temperature range of the magnetic refrigeration cycle is used.

[0005] Reference numeral 9 denotes a vertical movement mechanism for vertically moving the exhaust heat switch movable section 8, and reference numeral 10 denotes a rod connecting the vertical movement mechanism 9 and the exhaust heat switch movable section 8. Numeral 11 denotes a container for accommodating the movable part 8 of the exhaust heat switch, the magnetic body 12, and the regenerator 13. This container 11 is filled with a helium gas 14. The helium gas 14 is used for promoting heat transfer between the heat-dissipating switch movable section 8 and the magnetic body 12 and between the magnetic body 12 and the regenerator 13.

For example, when the Ericsson cycle is operated at a level of 20 k, DyNi ₂ having a magnetic transition temperature at 20 k is used as the magnetic body 12. For the regenerator 13, for example, Pb (lead) having a low volume and a large specific heat is used.

Reference numeral 15 denotes a vertical movement mechanism for moving the regenerator 13 up and down. Reference numeral 16 denotes a rod for connecting the regenerator 13 and the vertical movement mechanism 15. 17 is a magnetic storage unit
It is a spring to press down on.

Reference numeral 18 denotes a suspension rod for fixing the magnetic body 12, using FRP or the like having a low thermal conductivity. 19 is a heater for measuring the refrigerating power, 20 is a superconducting magnet 29
Helium for cooling the helium, 21 is the liquid helium 2
It is a liquid helium tank that stores 0.

An operation for realizing an Ericsson cycle in the magnetic refrigerator having the above configuration will be described below. When the upper end of the regenerator 13 contacts the magnetic body 12, the superconducting magnet 29 is excited. Then, the regenerator 13 is raised, and when the lower end of the regenerator 13 contacts the magnetic body 12, the superconducting magnet 29 is demagnetized. After that, the regenerator 13 is lowered again.

By repeating the above operation, the regenerator 13 has a temperature distribution in which the upper end has a high temperature TH and the lower end has a low temperature TL, and the operation of the magnetic Ericsson cycle can be started.

When the magnetic body 12 moves to the high temperature end of the regenerator 13 and the temperature reaches TH, the magnetic field of the superconducting magnet 29 is excited from 0 to the maximum value. At this time, since the temperature of the magnetic body 12 rises, the heat removal switch movable section 8 is moved to the magnetic body 1.
2 and is exhausted to the auxiliary refrigerator 5 (isothermal magnetization process).

When the temperature of the magnetic body 12 reaches TH again,
While keeping the magnetic field of the superconducting magnet 29 at the maximum value,
The regenerator 13 is raised by the vertically moving rod 16. The magnetic body 12 exchanges heat with the regenerator 13 and the temperature drops from TH to TL (equal magnetic field cooling process).

The magnetic body 12 moves to the low temperature end of the regenerator 13, the temperature becomes TL, and the magnetic field of the superconducting magnet 29 is demagnetized from its maximum value to zero. At this time, the temperature of the magnetic body 12 decreases, the heater 19 is turned on, and the magnetic body 12 absorbs heat (isothermal demagnetization process).

When the temperature of the magnetic body 12 reaches TL again,
With the magnetic field of the superconducting magnet 29 kept at 0, the regenerator 13 is lowered by the vertically moving rod 16. Magnetic body 1
2 exchanges heat with the regenerator 13 and the temperature rises from TL to TH (isomagnetic field heating process).

By repeating the cycle composed of the four steps as described above, the Ericsson type magnetic refrigerator shown in FIG. 3 can generate a low temperature intermittently.

[0016]

In a conventional magnetic refrigerator, as shown in FIG.
When the regenerator 13 moves, a frictional force proportional to the compression pressure of the spring 17 acts between the magnetic body 12 and the regenerator 13.

As a result, as shown in FIG. 4B, the magnetic body 12 is dragged by the regenerator 13 so as to be brought into a single hit state. Further, when the regenerator 13 moves, the magnetic body 12 and the regenerator 1 are moved.
The heat transfer surface 3 is further away as shown in FIG.

As a result, the effective heat transfer area between the regenerator 13 and the magnetic body 12 is reduced, the heat transfer becomes insufficient, and a long time is required for the regenerative process. Refrigeration output decreases. The present invention seeks to solve the above problems.

[0019]

[Means for Solving the Problems]

(1) According to the first aspect of the present invention, heat is removed from a magnetic material, a superconducting magnet for applying a magnetic field to the magnetic material, and the magnetic material that generates heat during excitation of the superconducting magnet. In a magnetic refrigerator including a heat switch and a regenerator that performs heat exchange by coming into contact with the magnetic body, a friction coefficient of an upper and lower surface of the magnetic body at a contact portion with the regenerator is at least smaller than the magnetic body. A sliding guide member is provided.

In the above, when the regenerator moves and the contact between the magnetic material and the regenerator becomes one-sided, the sliding chamber member made of a substance having a small coefficient of friction and installed on the upper and lower surfaces of the magnetic material serves as the regenerator. Contact.

At this time, since the magnetic body is easily slipped by the slide guide member, the one-sided contact state between the magnetic body and the regenerator is immediately eliminated, an effective heat transfer area is increased, and the magnetic body and the regenerator are cooled. The heat transfer performance can be improved.

(2) According to a second aspect of the present invention, in the magnetic refrigerator according to the first aspect of the present invention, a guide is provided which comes into contact with the upper and lower surfaces of the magnetic body and suppresses the vertical movement thereof. And

In the present invention, since the guide is provided in addition to the sliding guide member, the magnetic material is not dragged in the moving direction of the regenerator. Therefore, the regenerator can move while being in close contact with the magnetic body, and the heat transfer performance between the regenerator and the magnetic body can be further improved.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A magnetic refrigerator according to an embodiment of the present invention will be described with reference to FIG. In this embodiment, the heat insulating vacuum vessel 1 provided with the flange 2
And a regenerator 13 provided in a container 11 disposed inside the liquid nitrogen tank 3, and a side wall of the container 11 disposed on both sides of the regenerator 13. Spring 1 between
, A heater 19 provided below each magnetic body 12, and a liquid helium tank 21 provided between the liquid nitrogen tank 3 and the container 11. A superconducting magnet 29 that excites the body 12, an auxiliary refrigeration unit that is connected to the movable exhaust heat switch 8 provided in the container 11 via the cold head 6 and the copper block 7 and that is provided above the adiabatic vacuum container 1. Machine 5 and a magnetic refrigerator provided with up-and-down movement mechanisms 9 and 15 which are provided above the adiabatic vacuum vessel 1 and are connected to the heat-discharge switch movable section 8 and the regenerator 13 via rods 10 and 16, respectively. Since this part is the same as that of the conventional device, detailed description thereof is omitted.

In the embodiment shown in FIG. 1, in the above-mentioned magnetic refrigerator, the regenerators 1 on the upper surface and the lower surface of each magnetic body 12 are provided.
The sliding guide members 22a and 22b made of a low coefficient of friction material such as Teflon provided at the contact portions with the magnetic material 12 and the upper and lower surfaces of the respective magnetic members 12 are fixed to the inner surface of the side wall of the container 11 respectively. And guides 23a and 23b for preventing the magnetic body 12 from moving up and down.

In the above, the regenerator 13 moves,
When the magnetic body 12 and the regenerator 13 are brought into a state in which the magnetic body 12 and the regenerator 13 shown in FIG. 2B come into contact with each other from the state illustrated in FIG.
a, 22b contact the regenerator 13.

At this time, since the magnetic body 12 is easily slid by the slide guide members 22a and 22b, FIG.
It is easy to return to the state of surface contact shown in (c). Further, since the guide is provided, the magnetic body 12 is not dragged in the moving direction of the regenerator 13.

As a result, even if the regenerator 13 moves in the cold storage process, the magnetic body 12 is not dragged in the moving direction of the regenerator 13 and the distance between the regenerator 13 and the heat transfer surface of the magnetic body 12 is kept small. Can increase the effective heat transfer area.

Therefore, the heat transfer performance of the contact surface between the magnetic material 12 and the regenerator 13 in the cold storage process can be improved and the time required for the cold storage process can be shortened, so that a high-performance magnetic refrigerator can be realized.

[0030]

According to the present invention, there is provided a magnetic material, a superconducting magnet for exciting the magnetic material, a heat switch for discharging heat from the magnetic material, which generates heat during excitation by the magnet,
A magnetic refrigerator having a regenerator that performs heat exchange by contacting with the magnetic material, wherein a sliding guide member having a low coefficient of friction is provided at a contact portion between the upper and lower surfaces of the magnetic material and the regenerator. This allows the regenerator to be moved in close contact with the magnetic material, increasing the effective heat transfer area and improving the heat transfer performance between the regenerator and the magnetic material. Since the time required for the process is shortened, a high-performance magnetic refrigerator having a large refrigeration output can be realized.

Further, in addition to the sliding guide member, a guide is provided in contact with the upper and lower surfaces of the magnetic body and suppresses the vertical movement thereof, so that the heat transfer performance between the heat storage unit and the magnetic body is further improved. Becomes possible.

[Brief description of the drawings]

FIG. 1 is a sectional view of a magnetic refrigerator according to an embodiment of the present invention.

FIG. 2 is an operation explanatory view according to the embodiment, in which (a) shows a state in which a regenerator is stationary and is in surface contact with a magnetic body;
(B) is a state where the regenerator is moving and is in one-side contact with the magnetic body, and (c) is a state where the regenerator is further moved and the magnetic body is in surface contact.

FIG. 3 is a sectional view of a conventional magnetic refrigerator.

FIG. 4 is a diagram illustrating the operation of a conventional magnetic refrigerator.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Insulated vacuum container 2 Flange part 3 Liquid nitrogen tank 4 Liquid nitrogen 5 Auxiliary refrigerator 6 Cold head 7 Copper block 8 Exhaust switch movable part 9 Vertical movement mechanism 10 Rod 11 Container 12 Magnetic body 13 Regenerator 14 Helium gas 15 Regenerator Vertical movement mechanism 16 Rod 17 Spring 18 Hanging rod 19 Heater 20 Liquid helium 21 Helium tank 22a, 22b Sliding guide member 23a, 23b Guide 29 Superconducting magnet

Claims (2)

[Claims] 1. A magnetic body, a superconducting magnet for applying a magnetic field to the magnetic body, and a thermal switch for exhausting heat from the magnetic body that generates heat during excitation of the superconducting magnet;
In a magnetic refrigerator including a regenerator that performs heat exchange by contacting with the magnetic material, a sliding guide member having a friction coefficient smaller than that of the magnetic material at least in a contact portion between the upper and lower surfaces of the magnetic material and the regenerator. A magnetic refrigerator characterized by being installed. 2. The magnetic refrigerator according to claim 1, wherein
A magnetic refrigerator comprising a guide which is in contact with the upper and lower surfaces of the magnetic body and suppresses vertical movement thereof.